Technical Field
The invention relates to the art of tire pressure monitoring and inflation systems. More particularly, the invention relates to the monitoring of tire air pressure through components of a tire inflation system for heavy-duty vehicles, such as trucks and tractor-trailers or semi-trailers. Still more particularly, the invention is directed to a central tire pressure monitoring system that interfaces with a tire inflation system to check the pressure in all of the tires of a trailer of a heavy-duty vehicle at a single interface location on the trailer, without the need to provide power to the trailer, thereby providing a convenient way to monitor trailer tire pressure when multiple trailers are parked at a site.
Background Art
Heavy-duty vehicles typically include trucks and tractor-trailers or semi-trailers. Tractor-trailers and semi-trailers, which shall collectively be referred to as tractor-trailers for the purpose of convenience, include at least one trailer, and sometimes two or three trailers, all of which are pulled by a single tractor. All heavy-duty vehicles that are trucks or tractor-trailers include multiple tires, each of which is inflated with a fluid or gas, such as air, to an optimum or recommended pressure. This optimum or recommended tire pressure typically is referred to in the art as the target inflation pressure or the target pressure.
However, it is well known that air may leak from a tire, usually in a gradual manner, but sometimes rapidly if there is a problem with the tire, such as a defect or a puncture caused by a road hazard. As a result, it is necessary to regularly check the air pressure in each tire to ensure that the tires are not significantly below the target pressure and thus under-inflated. Should an air check show that a tire is under-inflated, it is desirable to enable air to flow into the tire to return it to the target pressure. Likewise, it is well known that the air pressure in a tire may increase due to increases in ambient air temperature, so that it is necessary to regularly check the air pressure in each tire to ensure that the tires are not unacceptably above the target pressure and thus over-inflated. Should an air check show that a tire is over-inflated, it is desirable to enable air to flow out of the tire to return it to the target pressure.
The large number of tires on any given heavy-duty vehicle setup makes it difficult to manually check and maintain the target pressure for each and every tire. This difficulty is compounded by the fact that trailers of tractor-trailers or trucks in a fleet may be parked at a site for an extended period of time, during which the tire pressure might not be checked. Any one of these trailers or trucks might be placed into service at a moment's notice, leading to the possibility of operation with under-inflated or over-inflated tires. Such operation may increase the chance of less-than-optimum performance and/or reduced life of a tire in service as compared to operation with tires at the target pressure, or within an optimum range of the target pressure.
Such a need to maintain the target pressure in each tire, and the inconvenience to the vehicle operator having to manually check and maintain a proper tire pressure that is at or near the target pressure, led to the development of prior art tire inflation systems. In these prior art systems, when there is power to the system, an operator selects a target inflation pressure for the vehicle tires. The system then monitors the pressure in each tire and attempts to maintain the air pressure in each tire at or near the target pressure by inflating the tire when the monitored pressure drops below the target pressure. These prior art tire inflation systems inflate the tires by providing air from the air supply of the vehicle to the tires by using a variety of different components, arrangements, and/or methods. Certain prior art systems are also capable of deflation, and these systems deflate the tires when the monitored pressure rises above the target pressure by venting air from the tires to atmosphere.
While being satisfactory for their intended functions, tire inflation systems of the prior art may experience disadvantages in certain situations. For example, as mentioned above, trailers of tractor-trailers from a fleet may be parked at a site for an extended period of time. Because any one of these trailers might be placed into service at a moment's notice, it is prudent for an owner or operator of a fleet to monitor the pressure in the tires of the parked trailers to ensure that tire pressure is maintained at or near a desired level in order to optimize the life of each tire. However, verification of tire pressure through prior art tire inflation systems is performed only when there is electrical power to the system, typically when the vehicle is operating. It is typically undesirable for a fleet owner to have power connected to each parked trailer to check tire pressure, as this is a time-consuming task that consumes manpower, as well as fuel to start up each vehicle, or other power, such as a separate electrical line, which is needed to power up the tire inflation system. All of these factors undesirably increase the cost of maintaining the fleet.
In the prior art, the only manner of checking or verifying the pressure in the tires of a fleet of parked trailers without providing power to each trailer has been for a technician to walk around each trailer and manually check the pressure in each tire with a tire pressure gauge. Because each trailer typically includes eight or more tires, this is an extremely time-consuming task, which again undesirably increases the cost of maintaining the fleet.
As a result, there is a need in the art for a tire pressure monitoring system that overcomes the disadvantages of the prior art by providing a central monitoring system that interfaces with a tire inflation system to check the pressure in all of the tires of a trailer of a heavy-duty vehicle from a single location, without the need to provide power to the trailer. The central tire pressure monitoring system of the present invention satisfies these needs, as will be described in detail below.